Php/docs/function.hash-init

• PHP Manual
• Hash Functions
• Initialize an incremental hashing context

hash_init

(PHP 5 >= 5.1.2, PHP 7, PECL hash >= 1.1)

hash_init — Initialize an incremental hashing context

Description

hash_init ( string $algo [, int $flags = 0 [, string $key = "" ]] ) : HashContext

Parameters

algo

Name of selected hashing algorithm (i.e. "md5", "sha256", "haval160,4", etc..). For a list of supported algorithms see hash_algos().

flags

Optional settings for hash generation, currently supports only one option: HASH_HMAC. When specified, the key must be specified.

key

When HASH_HMAC is specified for flags, a shared secret key to be used with the HMAC hashing method must be supplied in this parameter.

Return Values

Returns a Hashing Context for use with hash_update(), hash_update_stream(), hash_update_file(), and hash_final().

Changelog

Version	Description
7.2.0	Usage of non-cryptographic hash functions (adler32, crc32, crc32b, fnv132, fnv1a32, fnv164, fnv1a64, joaat) with HASH_HMAC was disabled.
7.2.0	Return HashContext instead of resource.

Examples

Example #1 Incremental hashing example

<?php$ctx = hash_init('md5');hash_update($ctx, 'The quick brown fox ');hash_update($ctx, 'jumped over the lazy dog.');echo hash_final($ctx);?>

The above example will output:

5c6ffbdd40d9556b73a21e63c3e0e904

See Also

• hash() - Generate a hash value (message digest)
• hash_algos() - Return a list of registered hashing algorithms
• hash_file() - Generate a hash value using the contents of a given file
• hash_hmac() - Generate a keyed hash value using the HMAC method
• hash_hmac_file() - Generate a keyed hash value using the HMAC method and the contents of a given file